Conventional plastics possess a surface resistance which is greater than 1000 Mohm. In order to prevent the accumulation of static electricity on plastics components, either they are finished with a conductive coating or conductive materials are incorporated into the plastic. The conductive coatings consist of a coating binder and a conductive pigment, for example carbon black or graphite. To achieve adequate conductivity, carbon black concentrations of from 10 to 30% must be used (company document from Degussa: in the Pigments series, Degussa-Pigmentru.beta.e for leitfahige Beschichtungen [Degussa pigment blacks for conductive coatings], Number 65, pages 8 to 15).
However, because of its high light absorption in the visible region of the spectrum, carbon black cannot be employed for transparent, light coatings. A further problem is the strong absorption of carbon black in the IR region, which leads, for example when solar radiation is incident, to the coated articles undergoing heating which is in many cases unwanted. Therefore, for light, conductive coatings, antimony-doped tin oxide is increasingly employed.
EP 487,366 describes antistatic and radio-transparent coatings for antennae of space satellites. The pigment used for this purpose consists of tin dioxide and titanium dioxide, which are doped with antimony. As an option it is possible to add to the coating composition a non-conducting, white pigment, for example TiO.sub.2, to improve the whiteness of the coating composition. Values of between 2 and 500 M.OMEGA. are given for the surface resistance of the coating. For antistatic coatings, for which in general a surface resistance of less than M.OMEGA. is required, the conductivity of this coating is too low.
When coating flexible PVC, additional problems arise in relation to the adhesion of the coating. The plasticizer contained in the plastic diffuses in the direction of the phase boundary between the PVC and the coating and destroys the adhesion of the coating to the plastics surface.